Generally, paging control is a technology with which a mobile terminal (mobile host) performs location registration in a paging area larger than a location registration area, thereby reducing the volume of control signals for location registration and also implementing power conservation in conjunction with intermittent reception technology of the mobile terminal.
For reducing the volume of control signals for location registration, consideration must be given to how much the effect of reducing the number of location registrations at a mobile terminal is cancelled by generation of a signal (paging notification packet) for notifying the mobile terminal of an incoming communication.
In this respect, conventional paging control has sought to reduce as much the volume of control signals for location registration as possible, by defining a paging control procedure unique to a mobile communications system and also forming a paging area which optimizes the number of location registrations and the number of times of paging.
Paging control in “Mobile IP” and its extended methods is used for reducing the transmission of “biding update packets” as location registration packets. A mobile terminal in paging control mode does not transmit a binding update packet to a controller apparatus (mobility control node) which manages the packet forwarding route, when it moves between location registration areas (subnets) belonging to the same paging area. A mobile terminal in paging control mode is notified of the arrival of packets addressed to the mobile terminal by a paging notification packet transmitted within a paging area of the mobile terminal. Thus, also in this technology, it is important to determine a paging area of an appropriate size.
Therefore, for a paging area forming method, various proposals and implementations have been made in each mobile communications system with consideration given to a communicating use and movement characteristics of a mobile terminal, the load conditions of a controller apparatus, and so on.
For example, a method is known in which, in each mobile communications system, a controller apparatus obtains the movement characteristics of a mobile terminal from access points (e.g., base stations) which the mobile terminal went through, location information on the mobile terminal measured by GPS, the movement speed of the mobile terminal, or the like, so as to form a paging area of an optimum configuration.
In conventional paging control, however, only one or several paging area forming methods (algorithms) are implemented which are premised on a certain communicating use and movement characteristics of a mobile terminal within a single mobile communications system.
Consequently, there is the problem that, in a universal IP network where various communicating uses and movement characteristics of mobile terminals are expected, use of the conventional paging control increases the case where premises on a communicating use and movement characteristics of a mobile terminal are not met, and cannot reduce the volume of control signals for location registration.
There is also the problem that, in order to reduce the volume of control signals for location registration by the conventional paging control in the universal IF network, it is necessary to implement a considerable amount of paging area forming methods to deal with all communicating uses and movement characteristics of mobile terminals which are expected in the universal IF network, resulting in increased implementation loads in controller apparatuses and mobile terminals.
The present invention has been made in view of the above problems, and has an object of providing a controller apparatus and a mobile terminal which enable forming an optimum paging area for a communicating use or movement characteristics of the mobile terminal by cooperation between the controller apparatus and the mobile terminal.